1. Field of the Invention
The present invention relates to a process for producing a heat-sensitive stencil sheet. Specifically, it relates to a novel process for producing a heat-sensitive stencil sheet which makes it possible to readily form a porous substrate layer of fibers with a uniform and dense fiber dispersion on a thermoplastic resin film.
2. Description of the Prior Art
In a prior art, a heat-sensitive stencil sheet is produced by adhering a thermoplastic resin film on a porous substrate such as a porous thin sheet with an adhesive. For example, one surface of an original and a resin film of a heat-sensitive stencil sheet are brought into contact with each other and irradiated by light from the side of the porous substrate of the heat-sensitive stencil sheet in order to generate heat at the black image portion of the original, thereby the heat-sensitive stencil sheet being engraved either by melt-perforating the film of the heat-sensitive stencil sheet with the aid of the generated heat or by reading the original image by an image sensor and then by melt-perforating the film of the heat-sensitive stencil sheet corresponding to the original image by means of a thermal head. The pictorial property of the printed matter obtained by using such a heat-sensitive stencil sheet is, however, influenced not only by the perforating property of the heat-sensitive stencil sheet but also by the fiber dispersibility in the substrate.
Since the heat-sensitive stencil sheet of the prior art used to be prepared by using a porous thin sheet as a substrate through a wet paper making process, then a film were glued to the resulting substrate, the process was complicated and it was difficult to prepare the heat-sensitive stencil sheet by using a single production line from beginning to end.